They went with Mercutio, who was invited.
Let's go crash it!
Benvolio
To check out the girls.
Romeo sees Juliet for the first time at her house. Her family (the Capulets) held a party, and Romeo and his friends Benvolio and Mercutio learned of it when they bumped into the Clown, Capulet's servant. Romeo was in love with Rosaline at that time, and Benvolio suggests that they go to this party, as Rosaline, who is a Capulet, would be there. However, Benvolio's goal is for Romeo to meet another girl and fall in love, which did happen; unfortunately, this other girl, which is Juliet, happens to be a Capulet as well.
Benvolio was planning to go to check out the girls. He talks Romeo into coming because Rosaline, the girl who refuses to listen to Romeo's protestations of love, will be there, partying it up. Romeo's intention is to hang around Rosaline, but Benvolio is hoping that some other girl who is at the party will make Romeo forget about her. This is a plan which is more successful that Benvolio can imagine.
Benvolio convinced Romeo to go to the Capulet's party.
No-one invites romeo to the party. Romeo and Mercutio come across a servant who cannot read and find out that the Capulets are hosting a party and that Rosaline (who Romeo thinks he is in love with) will be there. So they decide to go. Everyone will be wearing masks so no-one will recognise him. Tybalt finds out that they are there but Lord Capulet tells Tybalt not to start a fight since Romeo hasn't caused any trouble.
To the Capulets' backyard, where he sees Juliet on her balcony.
To the Capulets' backyard, where he sees Juliet on her balcony.
Romeo wants to crash the party because he knows Rosaline is invited. Benvolio wants Romeo to go, hoping he'll see a girl who will take his mind off of Rosaline. Does he ever.
Because Romeo has just experienced unrequited love, so Benvolio advises him to go to the Capulets' party to find someone else to love. At this point Romeo meets Juliet and are now secretly in love with each other. By BV
Romeo's friends, Mercutio and Benvolio, convince him to go to the Capulet's party to meet new young ladies. They encourage him to forget about his unrequited love for Rosaline and to have a good time at the party.